copyright cmassengale

copyright cmassengale
PROTEIN SYNTHESIS copyright cmassengale

DNA DNA contains genes, sequences of nucleotide bases These Genes code for polypeptides (proteins) Proteins are used to build cells and do much of the work inside cells copyright cmassengale

Amino Acid Structure copyright cmassengale

Polypeptides Amino acid chains are called polypeptides copyright cmassengale

Starting with DNA DNA ‘s code must be copied and taken to the cytosol In the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins) This process is called PROTEIN SYNTHESIS copyright cmassengale

Pathway to Making a Protein
DNA mRNA Read by ribosomes Protein copyright cmassengale

DNA  RNA  Protein Eukaryotic Cell Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein copyright cmassengale

RNA copyright cmassengale

Differences between DNA and RNA
Nucleic Acid Sugar Base Strands DNA Deoxyribose A, C, G, Thymine Double RNA Ribose Uracil Single copyright cmassengale

Structure of RNA Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded. copyright cmassengale

. Three Types of RNA Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized copyright cmassengale

Ribosomal RNA (rRNA) rRNA is a single strand 100 to 3000 nucleotides long Globular in shape Made inside the nucleus of a cell and exported to cytoplasm Associates with proteins to form ribosomes Site of protein Synthesis copyright cmassengale

Messenger RNA Long Straight chain of Nucleotides Copies DNA and carries the information for a specific protein Made up of 500 to nucleotides long, organized into 3-base codons copyright cmassengale

Remember the Complementary Bases
On DNA: A-T C-G On RNA: A-U copyright cmassengale

Genetic Code DNA contains a triplet code
Every three bases on DNA stands for ONE amino acid Each three-letter unit on mRNA is called a codon Most amino acids have more than one codon! 20 amino acids: 64 different triplets ALL organisms use the SAME code The fact that the genetic code is about universal in living things suggests that the code dates back to the first organisms on earth and that all living things are related.

The Genetic Code Example: AUG codes for Methionine

Transfer RNA (tRNA) Clover-leaf shape Single stranded molecule with attachment site at one end for an amino acid Opposite end has three nucleotide bases called the anticodon copyright cmassengale

Transfer RNA amino acid attachment site U A C anticodon copyright cmassengale

Codons and Anticodons The 3 bases of an anticodon are complementary to the 3 bases of a codon Example: Codon ACU Anticodon UGA UGA ACU copyright cmassengale

RNA Ad You are part of a marketing team tasked with designing a half page ad to sell RNA. You need to have a picture and slogan that will sell at least one of the types of RNA to consumers by showcasing its unique properties. Underneath your ad, write 3-5 sentences explaining how your ad will sell RNA. copyright cmassengale

Two Parts of Protein Synthesis
Transcription makes an RNA molecule complementary to a portion of DNA Translation occurs when the sequence of bases of mRNA DIRECTS the sequence of amino acids in a polypeptide

Transcription Translation
Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein. Translation

Transcription The process of copying the sequence of one strand of DNA, the template strand mRNA copies the template strand Requires the enzyme RNA Polymerase copyright cmassengale

Template Strand copyright cmassengale

Question: What would be the complementary RNA strand for the following DNA sequence? DNA 5’-GCGTATG-3’ copyright cmassengale

Answer: DNA 5’-GCGTATG-3’ RNA 3’-CGCAUAC-5’ copyright cmassengale

Transcription During transcription, RNA polymerase binds to DNA and separates the DNA strands RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA copyright cmassengale

RNA Polymerase copyright cmassengale

mRNA Transcript mRNA leaves the nucleus through its pores and goes to the ribosomes copyright cmassengale

Translation Translation is the process of decoding the mRNA into a polypeptide chain Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins copyright cmassengale

Ribosomes Made of a large and small subunit Composed of rRNA (40%) and proteins (60%) Have two sites for tRNA attachment --- P and A copyright cmassengale

Translation Three steps:
1. initiation: mRNA binds to ribosome at start codon (AUG) 2. elongation: amino acids linked 3. termination: stop codon (UAG, UAA, or UGA) signals ribosome to release mRNA

Step 1- Initiation mRNA transcript attaches to the small ribosomal subunit Small subunit attaches to large ribosomal subunit mRNA transcript copyright cmassengale

Ribosomes Large subunit P Site A Site mRNA A U G C Small subunit copyright cmassengale

Initiation 2-tRNA G aa2 A U 1-tRNA U A C aa1 anticodon A U G C U A C U U C G A hydrogen bonds codon mRNA copyright cmassengale

Step 2 - Elongation As ribosome moves, tRNA with their amino acids move into the ribosome Peptide bonds join the amino acids copyright cmassengale

Elongation 3-tRNA G A aa3 peptide bond aa1 aa2 1-tRNA 2-tRNA anticodon U A C G A U A U G C U A C U U C G A hydrogen bonds codon mRNA copyright cmassengale

aa1 peptide bond 3-tRNA G A aa3 aa2 1-tRNA U A C (leaves) 2-tRNA G A U A U G C U A C U U C G A mRNA Ribosomes move over one codon copyright cmassengale

peptide bonds 4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA 3-tRNA G A U G A A A U G C U A C U U C G A A C U mRNA copyright cmassengale

peptide bonds 4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA G A U (leaves) 3-tRNA G A A A U G C U A C U U C G A A C U mRNA Ribosomes move over one codon copyright cmassengale

peptide bonds U G A 5-tRNA aa5 aa1 aa2 aa4 aa3 3-tRNA 4-tRNA G A A G C U G C U A C U U C G A A C U mRNA copyright cmassengale

peptide bonds U G A 5-tRNA aa5 aa1 aa2 aa3 aa4 3-tRNA G A A 4-tRNA G C U G C U A C U U C G A A C U mRNA Ribosomes move over one codon copyright cmassengale

aa5 aa4 aa199 Termination aa3 primary structure of a protein aa200 aa2 aa1 terminator or stop codon 200-tRNA A C U C A U G U U U A G mRNA copyright cmassengale

End Product –The Protein!
The end products of protein synthesis is a primary structure of a protein A sequence of amino acid bonded together by peptide bonds aa1 aa2 aa3 aa4 aa5 aa200 aa199 copyright cmassengale

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